Luminescent properties of Tb3+ doped sodium silica germanate glasses

Tb3+-doped sodium silica germanate glasses were fabricated by conventional melt quenching technique with dopant concentrations of 0.3%mol and 0.9%mol. Their structural characteristics were analyzed through X-ray diffraction and Raman spectroscopy. The study of their optical properties was carried out through steady-state and time-resolved fluorescence spectroscopies. The emission spectra of both glasses are dominated by D-5(4) -> F-7(J) manifold transitions. The most intense band, associated with the D-5(4) -> F-7(5) transition, shows a clear split into two peaks (541 nm 550 nm) due to crystal field splitting. The decay of Tb3+ emission at 458 nm exhibits a non-exponential evolution accompanied by a shortening of its lifetime as the concentration of Tb3+ increases, due to a non-radiative Tb3+-Tb3+ energy transfer through the cross-relaxation mechanism [D-5(3), F-7(6)] -> [D-5(4), F-7(0)] between two terbium ions. The color coordinates at different excitation wavelengths lie in the yellow-green region of the Commission International de l'Eclairage chromaticity diagram. The results indicate that the studied glasses can be used in applications such as solid-state lighting and display devices.